Next of kin play an important role in organ donation. The aim of this study was to assess the extent to which explicitness of consent to organ donation by the deceased impacts the likelihood that next of kin will agree to organ donation of the deceased by using hypothetical cases. Results indicate that that people say they are more willing to agree to donate organs of those who explicitly consented to donate than those whose permission to donate is presumed. The degree of explicitness for the consent to donate by the deceased appears to influence the next of kin's decision about whether to agree to donation. This variation might explain the absence of differences in efficiency between various types of consent systems. (Contains 2 figures.)